Process of treating phosphate rock



Patented Nov. 19, 1929 UNITE STATE GRAY SINGLETON, OF FORT MEADE, AND ROBERT P. THORNTON, F LAKELAND, FLORIDA PROCESS OF TREATING EHOSPHATE ROCK N0 Drawing.

We have found that the large deposits of soft phosphate, or wavellite, which occur in Florida and in several European countries, is composed largely of aluminum phosphate and that this aluminum phosphate is readily soluble in alkaline solutions of either potash, for example, potassium carbonate, or ammonia5 forming water-soluble potassium or ammonium phosphate. Soft phosphate has 1 heretofore been regarded as practically worthless because of the fact that when it is treated with sulphuric acid in the usual process of making acid phosphate aluminum sulphate is formed which remains wet and can not be used in mixed fertilizers. In our process neither the potassium phosphate nor the ammonium phosphate has this tendency to remain wet and gummy after treatment.

The advantages of our process are as follows:

The soft phosphate can be mined at much less expense than the pebble orhard rock forms of calcium phosphate. Our process is less expensive than the usual acidulation of tri-calcium phosphate. The roduct of our process is water-soluble and is therefore in the best possible condition for rapid assimilation by plants. Our process will make a complete fertilizer in oneoperation since the ammonium phosphate and potassium phosphate, both of which can be made in one operation, contain all three of the essential plant foods. In our experiments, material containing as high as 19% P 0 has been made water-soluble by this process. This is higher than isusually obtained by the acid method with calcium phosphate. no acid. This is an advantage since free acidity is considered detrimental by some.

The operation of the process is simple. The soft phosphate is moistened with an alkaline solution of eitherammonia or potash as may be desired and is then allowed to stand for a short time so that the reaction maybe complete. The length of time depends upon the strength of the -solution. The product of this operation is then'dried in anilconvenient manner, for instance, a rotary 'ln, and is then ground and is read for application as a fertilizer. Using so The product has Application filed December 17, 1923. Serial No. 681,281.

phosphate, cyanamid and potash we find that we can make fertilizers of practically any desired grade in one operation.

What we claim is:

1. The herein described process of treat mg soft phosphate with a solution of ammonia to produce ammonium phosphate which is in a water soluble condition and suitable for plant food.

2. The herein described process of treating soft phosphate with an alkaline solution of both potash and ammonia to produce a complete fertilizer in one operation.

GRAY SINGLETON. ROBT. P. THORNTON. 

